The present invention relates to an actuator arm and more particularly to a hard drive actuator arm with reduced skew variation.
In disc drive technology it is becoming increasingly important that the relative angle between the read/write or transducer head and the data tracks changes very little, if at all, as the head moves across the surface of the disc. The relative angle between the head and the tracks is also known as skew. Magnetic recording discs can now achieve very large track densities and even a small change in the head skew can interfere with proper reading and writing of data on the disc.
Currently, head actuators consist of three types: linear, rotary, and combinations of both. Linear actuators consist of a sliding arm to which the head is attached. The arm is aligned along a radius of the disc and the head moves along the radius as the arm slides in and out without any variation in the skew. The problem with linear actuators is that they require a number of roller bearings to hold the arm. These bearings add unwanted inertia and frictional force to the system. Moreover, the relatively large amount of mass at the end of the actuator arm greatly reduces its speed, and hence, increases the access time of the disc drive system.
Rotary actuators pivot about a point or roll about a surface. The advantage of a rotary actuator is that it is much lighter and faster than a linear actuator. The major problem with the rotary actuator is that the skew angle between the head and the data tracks can vary by as much as 10 to 15 degrees as the head moves across the disc. Optimizing the position of the head and the dimensions of the head arm can reduce the skew angle variance; however, the variance may still be too large for high density disc drive systems. Perpendicular recording promises significant increases in disc capacity. However, because of write head design, track density increases demand that skew is less than 2 degrees across the surface of the disc. Thus, rotary actuators that have heads that compensate for the skew angle variance have been developed. However, they typically require a relatively large number of additional parts which correspondingly slows the access time.
Thus, there remains a need for an actuator arm which allows for reduced skew variation and quick access times.